An important property in rigid cooperative manipulation systems that has been studied thoroughly in the related literature is the regulation of internal forces. Internal forces are forces exerted by the agents at the grasping points that do not contribute to the motion of the object. While a certain amount of such forces is required in many cases (e.g., to avoid contact loss in multi-fingered manipulation), they need to be minimized in order to prevent object damage and unnecessary effort of the agents. Most works in rigid cooperative manipulation assume a certain decomposition of the interaction forces in motion-inducing and internal ones, without explicitly showing that the actual internal forces will be indeed regulated to the desired ones (e.g., [1]}, [2]}); [3]}, [4]}, [5]}, [6]}, [7]} analyze specific load decompositions based on whether they provide internal force-free expressions, whereas [8]} is concerned with the cooperative manipulation interaction dynamics. The decompositions in the aforementioned works, however, are based on the inter-agent distances and do not take into account the actual dynamics of the agents. The latter, as we show in this paper, are tightly connected to the internal forces as well as their relation to the total force exerted by the agents.
